In the recovery of oil and gas from subterranean formations it is common practice to fracture the hydrocarbon-bearing formation, providing flow channels for oil and gas. These flow channels facilitate movement of the hydrocarbons to the wellbore so they may be produced from the well. Without fracturing, many wells would not be economically viable.
In such fracturing operations, a fracturing fluid is hydraulically injected down a wellbore penetrating the subterranean formation. The fluid is forced down the interior of the wellbore casing, through perforations, and into the formation strata by pressure. The formation strata or rock is forced to crack open, and a proppant carried by the fluid into the crack is then deposited by movement of the viscous fluid containing proppant into the crack in the rock. The resulting fracture, with proppant in place to hold open the crack, provides improved flow of the recoverable fluid, i.e., oil, gas, or water, into the wellbore.
The perforations are generally produced by lowering a tool containing explosive charges into the wellbore to the depth of the formation of interest and detonating the explosive charges. In many cases, the wellbore casing or completion string is cemented to the subterranean formations, and the explosive charges penetrate the cement and casing.
These charges are shaped to provide outward forces and to blast a hole through the wellbore casing and into the hydrocarbon bearing formation.
Due to the hazards of handling, transporting, and using explosives in the remote locations where oil and gas wells are frequently located, it is desirable to eliminate the use of explosives as a means to create wellbore casing perforations.
Prior art fracturing systems often use expensive equipment to produce the perforations, and to control which of the perforations the fracturing fluid will flow and which area of the formation will be subject to stimulation. Once fracturing is complete, the equipment must remain in the wellbore, which is very expensive.